A pseudo random binary sequence (PRBS) method as shown in FIG. 1 has been conventionally used to measure a radio channel. In the PRBS method, a pseudo random code chip having a speed that is equal to that of a bandwidth to be measured is formed to transmit a transmission signal, and a receiver correlates the transmission signal and a sum of multipath waveforms corresponding to the transmission signal to obtain a frequency impulse response of a corresponding band.
Accordingly, a unit length of the pseudo random code is less than 1/W [Sec] for a measurement band having a bandwidth of W[Hz].
The unit length of the pseudo random code is required to have a short chip pulse that is inversely proportional to the bandwidth, according to a trend of the wideband mobile communication service and system.
Accordingly, complexity of realizing hardware is problematically increased to achieve accuracy in a channel measuring device of a 100 MHz bandwidth, compared to a channel measuring device of a 20 MHz bandwidth.
In a radio channel measuring method using the PRBS method, since a measurement bandwidth is determined according to a pseudo random (PN) chip rate, it is difficult to change the measurement bandwidth and it is difficult to concurrently measure the radio channel in a dual frequency band having the divided measurement band.
When the PRBS method is applied to a multi input multi output (MIMO) channel, a maximum Doppler measurement range is problematically reduced in a time division method as the number of antennas is increased.
Since it is assumed in the radio channel measuring method using the PRBS method in which the radio channel is not changed during a measuring period, an error may occur in a time-varying channel.
That is, the PRBS method is difficult to be realized, and it is difficult to measure an impact response characteristic of the radio channel in a bandwidth variation configuration.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.